On Mon, 1 Aug 2005 17:43:34 -0700, "greg knapp 5"
wrote:

If I have 4 feedlines, can I stack them vertically or
horizontally one foot apart from each other? How much is enough separation?
What other precautions do I need? Need they be twisted if they are not near
anything other than the other feed lines?
Any help is appreciated.

Hi Greg,

Feed lines that are terminated in balanced loads are self isolating.
The balance of the load is with respect to earth and is discussed
under the heading of Common Modality. So your problems are load
defined, not line defined. Naturally there is a continuum of linkage
between lines even in this best of all possible worlds. That
continuum spans from considerable-to-miniscule and it is, as you have
guessed, dependant upon spacing.

What constitutes considerable may be miniscule for another and I will
leave that determination up to you, as you have offered no limits nor
quantitative concerns. If you need a rule of thumb, keep all lines at
least 10 times their own pair-spacing apart. That is, if a twin lead
has 1 inch spacing between the conductors, keep that twin lead 10
inches from a similar feedline.

There are no doubt authoritative reports to offer a justification for
this rule, or any other offered. I would expect this would come from
Laport's work (which several correspondents here have copies of).

73's
Richard Clark, KB7QHC